A method for the preparation of an electrochromic ink and uses thereof

Abstract

The application discloses a preparation method of electrochromic ink, and specifically comprises the following steps: (1) adding tungsten powder into hydrogen peroxide to perform an oxidation reaction, then adding acetic anhydride and manganese dioxide to perform a reaction to obtain acetylated peroxypolytungstic acid powder; (2) adding the acetylated peroxypolytungstic acid powder and a modifier into anhydrous ethanol, then adding a yttrium salt solution to perform a reaction to obtain modified yttrium ion doped tungsten oxide sol; (3) aging the modified yttrium ion doped tungsten oxide sol to obtain modified yttrium ion doped tungsten oxide gel; (4) drying the modified yttrium ion doped tungsten oxide gel, grinding into powder, and then performing a heating treatment to obtain modified yttrium ion doped tungsten oxide powder; and (5) dissolving the modified yttrium ion doped tungsten oxide powder in a polar solvent. The electrochromic ink prepared by the method has excellent performance and can be used to prepare an electrochromic thin film on ITO glass by a spin coating method.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of novel ink materials, and particularly relates to a preparation method of electrochromic ink and application thereof. BACKGROUND

[0002] Color-changing materials refer to materials that can change color under certain conditions, among which, reversible color-changing materials are of great concern; because such materials have wide application prospects in many fields such as temperature sensors, optical instruments, electronic readers, and bionics. There are many types of color-changing materials, mainly including temperature-sensitive, light-sensitive, pressure-sensitive, and electrochromic types.

[0003] Electrochromic ink is a special ink; it has very wide applications, such as in electronic paper, smart cards, privacy protection devices, etc.; its advantages are fast reaction speed, high color contrast, and environmental friendliness, etc. Electrochromic ink can change color under the action of an external electric field; it should be noted that the color change of electrochromic ink is usually reversible, that is, the color of the ink can be controlled by repeated charging and discharging. The process of color change of electrochromic ink is actually the process of change of the structure of the molecules of the color-changing compound contained in the ink under the action of an electric field. The commonly used color-changing substances in electrochromic ink are usually organic color-changing compound molecules; however, electrochromic ink made of organic compound molecules also needs to add conductive substances and various additives (such as dispersants, binders, and defoamers, etc.); only in this way can the prepared electrochromic ink have conductivity and better fluidity and film-forming properties, which will also make the composition of the electrochromic ink more complex and greatly limit its application. In addition, organic color-changing compound molecules are usually limited by the number of cycles of molecular transformation and have a short service life, which further limits its commercial application (Wang Ziting, Yu Lanlan, Nie Zhiguo, Wang Huan. Mechanism and research progress of electrochromic materials [J]. Chemical Industry Science and Technology, 2023, 31(2): 82-86.). In view of this, the present application is proposed. SUMMARY

[0004] The purpose of the present application is to provide a preparation method of electrochromic ink and application thereof.

[0005] In order to achieve the above purpose, the solution of the present application is:

[0006] A preparation method of electrochromic ink, specifically comprising the following steps:

[0007] (1) adding tungsten powder into hydrogen peroxide to perform an oxidation reaction, then centrifugally separating to remove insoluble substances, slowly adding acetic anhydride into the obtained filtrate, then adding manganese dioxide, continuing to stir the obtained mixture to perform a reaction, then centrifugally separating again, washing and drying the obtained solid to prepare acetylated peroxypolytungstic acid powder;

[0008] (2) adding the acetylated peroxypolytungstic acid powder prepared in step (1) and a modifier into anhydrous ethanol, then adding a yttrium salt solution, continuing to stir the obtained mixture to be uniform to prepare a modified yttrium ion doped tungsten oxide sol;

[0009] (3) aging the modified yttrium ion doped tungsten oxide sol prepared in step (2) to prepare a modified yttrium ion doped tungsten oxide gel;

[0010] (4) drying the modified yttrium ion doped tungsten oxide gel prepared in step (3) to grind into powder, then performing a heating treatment to the obtained powder to prepare a modified yttrium ion doped tungsten oxide powder;

[0011] (5) dissolving the modified yttrium ion doped tungsten oxide powder prepared in step (4) in a polar solvent to prepare the electrochromic ink.

[0012] Further, the oxidation reaction temperature in step (1) is -5-0℃.

[0013] Further, the stirring reaction temperature in step (1) is first reacted at -5-0℃, then continues to react at room temperature.

[0014] Further, the modifier in step (2) is one of β-cyclodextrin, carboxymethyl chitosan, β-glucan or polyethylene glycol 2000.

[0015] Further, the yttrium salt in step (2) is one of yttrium nitrate or yttrium chloride.

[0016] Further, the heating temperature in step (4) is 250-550℃.

[0017] Further, the polar solvent in step (5) is one of dimethylformamide or N-methylpyrrolidone.

[0018] The electrochromic ink prepared by the preparation method of the aforementioned electrochromic ink is composed of a modified yttrium ion doped tungsten oxide powder and a polar solvent.

[0019] The aforementioned electrochromic ink is applied in the preparation of an electrochromic film.

[0020] The principle of the preparation method of the electrochromic ink provided by the application is:

[0021] The preparation method of the electrochromic ink provided by the present application is to prepare modified yttrium ion doped tungsten oxide powder by using sol-gel method with high molecular modifier (such as β-cyclodextrin, carboxymethyl chitosan, β-glucan or polyethylene glycol 2000) and metal ion yttrium as dopant, and then dissolving the obtained tungsten oxide powder in a polar solvent. The specific color changing principle is that when a negative potential is applied to the modified yttrium ion doped tungsten oxide, electrons and yttrium ions will be injected into the tungsten oxide at the same time to make the tungsten oxide become blue; and when a positive potential is applied, electrons and yttrium ions will leave the tungsten oxide at the same time to make it return to the original transparent colorless. However, the thin film prepared by using the electrochromic ink prepared by using unmodified tungsten oxide powder usually has a smaller specific surface area, which is not conducive to the diffusion of conductive ions in the thin film, which will lead to the electrochromic performance of the obtained thin film not being ideal. The method provided by the present application uses two different modifiers to modify the WO3 powder, wherein the high molecular modifier can increase the specific surface area of the tungsten oxide, thereby being conducive to improving the diffusion and migration ability of yttrium ions in the thin film, and further improving the electrochromic reversibility of the thin film and shortening the coloring / bleaching response time; and the doping of yttrium ions can reduce the crystal defects in the tungsten oxide thin film, thereby improving the stability of the thin film.

[0022] The gain effect of the preparation method of the electrochromic ink provided by the present application and its use is as follows:

[0023] (1) The electrochromic ink prepared by the method provided by the present application has the advantages of good dispersibility and stability, and can form stable ink droplets, and has application prospect in preparing electrochromic thin film on various conductive substrates by inkjet printing.

[0024] (2) The electrochromic ink prepared by the method provided by the present application successfully prepares electrochromic thin film on ITO glass by spin coating method, and the prepared thin film has excellent performance: the color changing contrast can reach 40.3%, the coloring time is 3.1 seconds, and the bleaching time is 1.8 seconds.

[0025] (3) The preparation method of the electrochromic ink provided by the present application also has the advantages of simple process, mild conditions and simple operation. DETAILED DESCRIPTION

[0026] The present application will be further described in detail in combination with the following examples. It should also be understood that the following examples are only used to further illustrate the present application, and cannot be understood as limiting the protection scope of the present application. The specific mass, reaction time and temperature, process parameters and the like in the examples are only one example in the appropriate range, and some non-essential improvements and adjustments made by those skilled in the art according to the above content of the present application all belong to the protection scope of the present application.

[0027] The reagents used are commercially available and are used without further purification unless otherwise specified.

[0028] Example 1:

[0029] The preparation steps of the electrochromic ink are as follows:

[0030] (1) Under ice bath and vigorous stirring, 6.5 g of tungsten powder (purity of 98%) was slowly added to 40 ml of hydrogen peroxide solution (concentration of 30%), after 1 hour of reaction, a small amount of insoluble substance was removed by centrifugal separation, then 40 ml of acetic anhydride (purity of 98.5%) was slowly added dropwise to the obtained filtrate, after half an hour of reaction, 0.3 g of manganese dioxide was added, and the reaction was continued under ice bath and stirring for half an hour, then the reaction was continued at room temperature for 2 hours under stirring; again centrifugal separation was performed, and the collected solid was dried in a vacuum drying oven at 60°C to obtain acetylated peroxypolytungstic acid powder 8.4 g;

[0031] (2) 1 g of the acetylated peroxypolytungstic acid powder prepared in step (1) and 0.3 g of carboxymethyl chitosan were added to 10 ml of anhydrous ethanol and stirred uniformly, then 2 ml of yttrium nitrate solution (dissolved in deionized water, concentration of 1%) was slowly added dropwise, and the obtained mixture was stirred uniformly to prepare a carboxymethyl chitosan modified yttrium ion doped tungsten oxide sol;

[0032] (3) The carboxymethyl chitosan modified yttrium ion doped tungsten oxide sol prepared in step (2) was placed in a microwave reaction tank for heat aging, under the conditions of microwave power of 300 W and temperature of 80°C, the reaction was continued for half an hour to prepare a carboxymethyl chitosan modified yttrium ion doped tungsten oxide gel;

[0033] (4) The carboxymethyl chitosan modified yttrium ion doped tungsten oxide gel prepared in step (3) was ground into powder, then the obtained solid powder was washed with 5 ml of anhydrous ethanol and 5 ml of deionized water in sequence, the obtained solid powder was dried at 110°C for 3 h, then was placed in a muffle furnace and heated at 300°C for 1 h to prepare a heat treated carboxymethyl chitosan modified yttrium ion doped tungsten oxide powder, which was recorded as CS-Y 3+ / WO3;

[0034] (5) 0.1 g of the heat treated carboxymethyl chitosan modified yttrium ion doped tungsten oxide powder prepared in step (4) was dissolved in 1 ml of dimethylformamide or N-methyl pyrrolidone to prepare the electrochromic ink, which was recorded as CS-Y 3+ / WO3-1.

[0035] Example 2:

[0036] The electrochromic ink was prepared according to Example 1, except that the amount of yttrium nitrate solution in step (2) was changed to 1 ml, and the remaining steps were the same as Example 1. The obtained electrochromic ink was recorded as CS-Y. 3+ / WO3-2.

[0037] Example 3

[0038] The electrochromic ink was prepared according to Example 1, except that the amount of yttrium nitrate solution in step (2) was changed to 3 ml, and the remaining steps were the same as Example 1. The obtained electrochromic ink was recorded as CS-Y 3+ / WO3-3.

[0039] Example 4

[0040] The electrochromic ink was prepared according to Example 1, except that the amount of yttrium nitrate solution in step (2) was changed to 4 ml, and the remaining steps were the same as Example 1. The obtained electrochromic ink was recorded as CS-Y 3+ / WO3-4.

[0041] Example 5

[0042] The electrochromic ink was prepared according to Example 1, except that the carboxymethyl chitosan in step (2) was replaced by β-cyclodextrin, and the remaining steps were the same as Example 1. The obtained electrochromic ink was recorded as β-CD-Y 3+ / WO3-5.

[0043] Example 6

[0044] The electrochromic ink was prepared according to Example 1, except that the carboxymethyl chitosan in step (2) was replaced by β-glucan, and the remaining steps were the same as Example 1. The obtained electrochromic ink was recorded as β-DT-Y 3+ / WO3-6.

[0045] Example 7

[0046] The electrochromic ink was prepared according to Example 1, except that the carboxymethyl chitosan in step (2) was replaced by polyethylene glycol 2000, and the remaining steps were the same as Example 1. The obtained electrochromic ink was recorded as PEG-Y 3+ / WO3-7.

[0047] Example 8

[0048] The electrochromic film was prepared as follows:

[0049] (1) Indium Tin Oxide glass (ITO glass) was sequentially put into acetone, anhydrous ethanol and deionized water for ultrasonic cleaning for 20 minutes, and then taken out and dried, and then put into ozone for continuous treatment for half an hour to obtain clean ITO glass;

[0050] (2) The CS-Y 3+ / WO3-1 prepared in Example 1 was spin-coated on ITO glass to form a film, and was annealed at 300℃ once after each spin-coating, and was spin-coated for 3 times, and then was treated in ozone for half an hour to obtain the electrochromic film.

[0051] The electrochromic film was characterized according to the method provided in the reference (Huang Jia-mu, Xu Ai-jiao, Mu Wei-peng. Electrochromic performance of Ni-doped WOx thin film [J]. Journal of Materials Science and Engineering, 2008, 26 (2), 177-180.).

[0052] The color change reaction of the electrochromic film was carried out in a two-electrode electrochemical cell, the ITO glass coated with the electrochromic film was used as the working electrode, the pure ITO glass was used as the counter electrode, the electrolyte was 1M LiClO4 / PC solution, and the voltage applied between the two electrodes was 3V. The color change reaction results were as follows: the color change contrast reached 40.3%, the coloring time was 3.1 seconds, and the bleaching time was 1.8 seconds.

[0053] After the film completed the color change reaction, it was taken out from the electrochemical cell, dried with filter paper, and then immediately detected the transmittance of the film on the ultraviolet spectrophotometer after blowing dry with clean air. The transmittance was 93.8%.

[0054] The physical property test results of the prepared electrochromic ink were as follows: the viscosity was 3.5 mPa·s, the surface tension was 39.2 mN / m, and the density was 1.76 g / cm 3 , and stable ink droplets could be formed.

[0055] Example 9

[0056] The preparation steps of the electrochromic film were referred to Example 8, except that CS-Y 3+ / WO3-1 in step (2) of Example 8 was replaced by CS-Y 3+ / WO3-2, and the remaining steps were the same as Example 1; and the performance of the obtained electrochromic film was characterized according to Example 8.

[0057] The color change reaction results were as follows: the color change contrast reached 35.6%, the coloring time was 3.6 seconds, and the bleaching time was 2.2 seconds. The transmittance was 94.2%.

[0058] Example 10

[0059] The preparation steps of the electrochromic film refer to Example 8, except that CS-Y 3+ / WO3-1 is replaced by CS-Y 3+ / WO3-3, and the remaining steps are the same as in Example 1; the performance of the obtained electrochromic film is characterized according to Example 8.

[0060] The results of the color change reaction are: the color change contrast reaches 38.4%, the coloring time is 2.1 seconds, and the bleaching time is 1.6 seconds. The light transmittance is 88.9%.

[0061] Example 11

[0062] The preparation steps of the electrochromic film refer to Example 8, except that CS-Y 3+ / WO3-1 is replaced by CS-Y 3+ / WO3-4, and the remaining steps are the same as in Example 1; the performance of the obtained electrochromic film is characterized according to Example 8.

[0063] The results of the color change reaction are: the color change contrast reaches 35.2%, the coloring time is 1.9 seconds, and the bleaching time is 1.2 seconds. The light transmittance is 88.2%.

[0064] Example 12

[0065] The preparation steps of the electrochromic film refer to Example 8, except that CS-Y 3+ / WO3-1 is replaced by β-CD-Y 3+ / WO3-5, and the remaining steps are the same as in Example 1; the performance of the obtained electrochromic film is characterized according to Example 8.

[0066] The results of the color change reaction are: the color change contrast reaches 33.3%, the coloring time is 4.2 seconds, and the bleaching time is 3.0 seconds. The light transmittance is 91.0%.

[0067] Example 13

[0068] The preparation steps of the electrochromic film refer to Example 8, except that CS-Y 3+ / WO3-1 is replaced by β-DT-Y 3+ / WO3-6, and the remaining steps are the same as in Example 1; the performance of the obtained electrochromic film is characterized according to Example 8.

[0069] The results of the color change reaction are: the color change contrast reaches 35.9%, the coloring time is 6.1 seconds, and the bleaching time is 3.3 seconds. The light transmittance is 87.3%.

[0070] Example 14

[0071] The preparation steps of the electrochromic film refer to Example 8, except that the spin-coating times in step (2) are changed from 3 to 4, and the rest of the steps are the same as in Example 1; the performance of the obtained electrochromic film is characterized according to Example 8. 3+ / WO3-1 is replaced by PEG-Y 3+ / WO3-7, and the rest of the steps are the same as in Example 1; the performance of the obtained electrochromic film is characterized according to Example 8.

[0072] The results of the color change reaction are: the color change contrast reaches 31.7%, the coloring time is 9.4 seconds, and the bleaching time is 4.8 seconds. The light transmittance is 89.7%.

[0073] Example 15

[0074] The preparation steps of the electrochromic film refer to Example 8, except that the spin-coating times in step (2) are changed from 3 to 4, and the rest of the steps are the same as in Example 1; the performance of the obtained electrochromic film is characterized according to Example 8.

[0075] The results of the color change reaction are: the color change contrast reaches 33.9%, the coloring time is 2.8 seconds, and the bleaching time is 2.1 seconds. The light transmittance is 83.2%.

[0076] Example 16

[0077] The preparation steps of the electrochromic film refer to Example 8, except that the annealing temperature in step (2) is changed from 300°C to 350°C, and the rest of the steps are the same as in Example 1; the performance of the obtained electrochromic film is characterized according to Example 8.

[0078] The results of the color change reaction are: the color change contrast reaches 29.2%, the coloring time is 4.3 seconds, and the bleaching time is 2.7 seconds. The light transmittance is 94.2%.

[0079] Example 17

[0080] The preparation steps of the electrochromic film refer to Example 8, except that the annealing temperature in step (2) is changed from 300°C to 250°C, and the rest of the steps are the same as in Example 1; the performance of the obtained electrochromic film is characterized according to Example 8.

[0081] The results of the color change reaction are: the color change contrast reaches 34.5%, the coloring time is 3.2 seconds, and the bleaching time is 2.1 seconds. The light transmittance is 81.3%.

Claims

1. A method for preparing an electrochromic ink, characterized in that, Specifically comprising the following steps: (1) adding tungsten powder into hydrogen peroxide to perform oxidation reaction, then centrifugally separating to remove insoluble substances, slowly adding acetic anhydride into the obtained filtrate, then adding manganese dioxide, continuing to stir the obtained mixture to perform reaction, then centrifugally separating again, washing and drying the obtained solid to prepare acetylated peroxypolytungstic acid powder; (2) adding the acetylated peroxypolytungstic acid powder prepared in step (1) and a modifier into anhydrous ethanol, then adding yttrium salt solution, continuing to stir the obtained mixture to be uniform to prepare modified yttrium ion doped tungsten oxide sol; the modifier is one of β-cyclodextrin, carboxymethyl chitosan, β-glucan or polyethylene glycol 2000; (3) aging the modified yttrium ion doped tungsten oxide sol prepared in step (2) to prepare modified yttrium ion doped tungsten oxide gel; the aging condition is that microwave power is 300 W, and the temperature is 80 ℃, and the microwave reaction is performed for half an hour; (4) drying the modified yttrium ion doped tungsten oxide gel prepared in step (3) to grind into powder, and heating the obtained powder to prepare modified yttrium ion doped tungsten oxide powder; (5) dissolving the modified yttrium ion doped tungsten oxide powder prepared in step (4) in a polar solvent to prepare the electrochromic ink.

2. The method for preparing an electrochromic ink according to claim 1, characterized in that, The oxidation reaction temperature in step (1) is -5-0 ℃.

3. The method for preparing an electrochromic ink according to claim 1, characterized in that, The stirring reaction temperature in step (1) is first -5-0 ℃, then continues to be room temperature.

4. The method for preparing an electrochromic ink according to claim 1, characterized in that, The yttrium salt in step (2) is one of yttrium nitrate or yttrium chloride.

5. The method for preparing electrochromic ink according to claim 1, characterized in that, The heating temperature in step (4) is 250-550 ℃.

6. The method of claim 1, wherein the electrochromic ink is prepared by the steps of: The polar solvent in step (5) is one of dimethylformamide or N-methylpyrrolidone.

7. An electrochromic ink prepared according to the method of any one of claims 1 to 6. The electrochromic ink is composed of modified yttrium ion doped tungsten oxide powder and a polar solvent.

8. An electrochromic ink prepared by the preparation method of the electrochromic ink according to any one of claims 1-6 or the application of the electrochromic ink according to claim 7 in preparing an electrochromic film.